The present invention relates to a control method for controlling a data transfer device, a data transfer circuit, and a disk array device.
The content of data handled by the information processing systems of recent years has become more and more important, which has in turn established a need for the reliability of storage devices. In a known method for increasing the reliability of storage devices, a security code, such as an LRC (Longitudinal Redundancy Check) code, is added to data that is stored in a storage device, such as a hard disk. Data handling between a storage device and an information processing device is performed in block units, and the security code is also added in block units.
Therefore, the methods for connecting to a storage device have diversified in recent years, and the adoption of technologies for linking information processing devices and storage devices by means of networks, as in the case of Fibre Channels, an iSCSI (Internet SCSI), and so forth, has begun. In an environment where information processing devices and storage devices are connected by a network, the information processing devices and storage devices are connected by a plurality of channels, and blocks of data transmitted from an information processing device to a storage device are sometimes transmitted on the network in different data-block sizes. For this reason, a situation may arise where only a portion of a block transmitted from the information processing device reaches the storage device. Further, there may also be transmissions in which a portion of a certain block and a portion of a block that is different from this block are mixed. Thus, a situation may arise where the storage device is unable to receive data blocks as serial data in the order in which this data is written to successive areas of the storage device.
However, in the case of conventional storage devices, there is the premise that at least one block's worth of data will be serially transmitted in the order of addresses stored in the storage device, which is not reconcilable with a situation where only a portion of a block is transmitted, as in the case of the network-connected embodiment referred to above.